Laser ablation synthesis of new gold arsenides using nano-gold and arsenic as precursors. Laser desorption ionisation time-of-flight mass spectrometry and spectrophotometry Lubomír Prokeš 1,2,3 , Eladia María Peña-Méndez 4 , José Elias Conde 4 , Nagender Reddy Panyala 1 , Milan Alberti 1,2,3 and Josef Havel 1,2,3 * 1 Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A14, 625 00 Brno, Czech Republic 2 Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic 3 CEPLANT, R&D Center for Low-Cost Plasma and Nanotechnology Surface Modifications, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic 4 Department of Analytical Chemistry, Nutrition and Food Science, Faculty of Chemistry, University of La Laguna, Campus de Anchieta, 38071 La Laguna, Tenerife, Spain RATIONALE: Currently, a limited number of gold arsenides have been described, some of which have important industrial applications, Laser ablation synthesis (LAS) has been employed in an attempt to generate some novel gold arsenide compounds. METHODS: LAS of gold arsenides was performed using nano-gold (NG) and arsenic as precursors. The clusters formed during laser desorption ionisation (LDI) were analysed by mass spectrometry using a quadrupole ion trap and reflectron time-of-flight analyser to determine the stoichiometry. UV/VIS spectrophotometry was used to follow possible hydrothermal synthesis of gold arsenides. RESULTS: LAS of NG yielded singly charged gold clusters Au m +(À) (m =1–35). LAS of bulk arsenic and nano-arsenic produced As n +(À) clusters with n =2–10 and n =2–20, respectively. Laser ablation of Au-As nano-composites or NG-As mixtures generated Au m +(À) (m =1–12), As n +(À) (n =3–4), and several series of Au m As n +(À) (m =1–60, n =1–18) clusters. Over 450 species of gold arsenide clusters and 212 mixed chlorinated Au m As n Cl x clusters were detected and their stoichiometry determined. CONCLUSIONS: Many new gold arsenides were synthesised via LAS for the first time with Au-As composites and NG-As mixtures of different Au:As ratios using mass spectrometry to determine cluster stoichiometry. The resolved stoichiometry of Au m As n clusters determined in this study could accelerate the development of advanced Au-As nano-materials. Copyright © 2014 John Wiley & Sons, Ltd. Arsenides of various metals are found as naturally occurring minerals. [1,2] While arsenic may play an important role in the formation of gold deposits, gold arsenides are not found in nature. [3–5] The first attempts to synthesize gold arsenides began in the early 20th century and produced Au 3 As and Au 4 As 3 [6] or AuAs [7] compounds. The solubility of arsenic in metallic gold is quite high [2,8–10] and the alloys produced are usually brittle, white or grayish-white, glass-like materials. [2] Exposing liquid gold to arsenic fumes produces white and very brittle gold arsenide. [10] Recently, gold-arsenic compounds were synthesized as prospective materials in microelectronics, including AuAs 2– (with Na + ), [11] [Au 2 (As 7 ) 2 ] 4– (with K + , Rb + , Cs + ) [12] and AuAs 2 3– (with La 3+ , Nd 3+ , Sm 3+ , Gd 3+ , and Tb 3+ ). [13] It has been shown that laser desorption ionisation time-of- flight mass spectrometry (LDI-TOF-MS) is a powerful technique for the generation and study of clusters formed during the laser ablation synthesis (LAS) of various solid materials. This process has been described for the formation of arsenic and arsenic sulphide clusters, [14] AgSbS 2 , [15] zinc oxide [16] and zinc sulphide [17] clusters, gold phosphides, [18] gold tellurides, [19] lanthanide oxide clusters with incorpo- rated heterovalent metal ions, [20] and carbon clusters from nano-diamonds. [21] LAS has also been used for the analysis of various solid material nano-layers such as As-S-Se [22] and As-Se [23] glasses, phosphorus nitride [24] and titanium carbides, [25] where the identification of structural fragments of solids using LDI-TOF-MS has been demonstrated. In the case of gold, several clusters, Au n + (n =1–35), were detected in the mass spectra of nano-gold (NG). [18,26,27] The structure of Au m gold clusters is planar up to m = 10, while for higher values of m, the structure is three-dimensional. [28–36] For m = 16–18, fullerene-like structures have been observed. [37] For arsenic the cluster structures can only be calculated using quantum chemistry [38–44] and the structure * Correspondence to: J. Havel, Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A14, 625 00 Brno, Czech Republic. E-mail: havel@chemi.muni.cz Copyright © 2014 John Wiley & Sons, Ltd. Rapid Commun. Mass Spectrom. 2014, 28, 577–586 Research Article Received: 13 November 2013 Revised: 20 December 2013 Accepted: 23 December 2013 Published online in Wiley Online Library Rapid Commun. Mass Spectrom. 2014, 28, 577–586 (wileyonlinelibrary.com) DOI: 10.1002/rcm.6815 577